Marriage counselors have couples role-play, each one taking the other spouse’s part. Psychologists have rapists and other criminals describe their crime from the point of view of the victim. Like novelists or moviemakers, their purpose is to transport people, mentally, into the mind of another.

Now, neuroscientists have shown that they can make this experience physical, creating a “body swapping” illusion that could have a profound effect on a range of therapeutic techniques. At the annual meeting of the Society for Neuroscience last month, Swedish researchers presented evidence that the brain, when tricked by optical and sensory illusions, can quickly adopt any other human form, no matter how different, as its own.

The technique is simple. A subject stands or sits opposite the scientist, as if engaged in an interview. Both are wearing headsets, with special goggles, the scientist’s containing small film cameras. The goggles are rigged so the subject sees what the scientist sees: to the right and left are the scientist’s arms, and below is the scientist’s body.

To add a physical element, the researchers have each person squeeze the other’s hand, as if in a handshake. Now the subject can see and “feel” the new body. In a matter of seconds, the illusion is complete. In a series of studies, using mannequins and stroking both bodies’ bellies simultaneously, the Karolinska researchers have found that men and women say they not only feel they have taken on the new body, but also unconsciously cringe when it is poked or threatened.